Gary is correct. Every Carnival ship I have been on has had the outlet in the same location (which thanks to Gary's picture) by the phone. There is also a razor outlet in the bath room but it is only good enough for charging.
You don't really need an extension cord, just a multi outlet converter (or one of the short ext cords that has the multi outlet head on it. Then the only time you need that is if you want to charge your phone and camera at the same time.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013